FIELD OF INVENTION
The invention relates to a folding device utilized for folding of flat material, preferably paper, including folding blades arranged for reciprocating movement in the direction perpendicular to a material to be folded.
More particularly, the invention relates to a drive system for folding blades in sheet-processing machines which have at least one blade-folding mechanism, with one pair of folding rollers arranged parallel to each other and driven in opposite-rotating directions and provided with a folding blade movable in the direction of the roller gap between the rollers.
It is known from the FRG Allowed Application 1,611,344 that the reciprocating movement of the folding blades into and out of contact with a material being folded may be caused by compressed air. It is furthermore known how to actuate folding blades by magnets. These drive systems have the disadvantage that they work relatively slowly and cannot fulfill the demands for output at high working working cycles. They also do not allow materializing of predetermined functions of power transmission as a basis for appropriate folding methods.
Furthermore, counter-controlled folding blade drives are known, wherein clutches with electrical, mechanical, or pneumatic actuation are interposed. These solutions have the disadvantage that the continual sequences of momentary starting and braking will cause heating-up and wear of the parts of the drive arrangement. In this case, changes of mechanical and electrical parameters will occur during operation, and will, on their part, influence the folding sequence.